This week offered a typical example of the disconnect that’s emerged between the United States and the rest of the globe. The eyes of the world are on the climate talks in Copenhagen, while the American political establishment instead watches Gen. Stanley McChrystal and Ambassador Karl Eikenberry offer testimony on Afghanistan to Congress. The simple fact of the matter is that what happens -- or doesn’t -- in Copenhagen is much more likely to be remembered in history books than the details of America’s effort to stabilize Afghanistan. Either concrete progress will be made toward a global effort to forestall catastrophic climate change or else we risk slipping backward down the slope and undoing all the effort of recent years.

And given how daunting the task is, it’s worth emphasizing how far we have come. For years, the idea that the European Union could keep with the Kyoto protocol and reduce emissions was treated as fantasy. Conventional wisdom held that the EU’s cap-and-trade system was plagued with problems. It’s true that the very beginning of the program went awry and handed out too many permits, but today all EU members save Austria have hit their targets, and on average, the union is ahead of schedule in meeting its goals. Japan, too, has met its Kyoto targets and its newly elected government has promised much more aggressive action to curb greenhouse gases and is urging the rest of the world to follow. In Australia, efforts to implement an emissions-trading scheme have run into trouble due to obstruction from the right wing of the more conservative party, but the resulting political crisis appears to favor the Labor Party and the eventual adoption of emissions limits.

Perhaps more impressive, China and India -- two countries that would supposedly never agree to serious environmental measures -- have both stepped up to the plate with commitments to substantially reduce emissions relative to trend. That’s not good enough, it’s true. But it’s a huge step in the right direction. And continued carping about China and India obscures the basic fact that what’s needed to press them in the direction of tougher measures is for the United States to join Europe and Japan in urging them. For that to happen, the U.S. needs to pass comprehensive clean-energy legislation.

Much of the American elite has a tendency to discount the extent to which greater American effort really would be decisive. Overgeneralizing from a recent decline in the number of Americans who say they believe in global warming, many in the Beltway assume that the developing world has likewise lost interest and thereby rationalize away American inaction. The reality, as revealed in a BBC poll earlier this week, is just the reverse. Worldwide levels of concern about climate change are increasing, and support for action is strong in major developed and developing economies. In both China and India, a majority -- a larger majority than in the United States -- say they favor government investment to combat climate change even if it hurts the economy.

Indeed, on measure after measure it’s the American public -- driven by a massive disinformation campaign by the pollution lobby and a feckless media that rarely seems capable of telling the truth -- that’s the most hesitant to take action.

Which is to say that we ourselves -- especially the ever-obstructionist United States Senate -- are the main barriers to serious coordinated international action. And it’s frankly a bit ridiculous. It’s true, as critics say, that reducing carbon emissions requires a significant national effort. But the United States undertakes significant national efforts all the time. In its estimation of the climate bill that passed the House months ago, the Congressional Budget Office concluded that "the net annual economywide cost of the cap-and-trade program in 2020 would be $22 billion" before considering the benefits of averting catastrophic climate change.

By contrast, we spent an average of $130 billion a year on the wars in Afghanistan and Iraq, every year from 2003 to 2009, according to the Congressional Research Service. For 2010, the Obama administration requested $138.6 billion and the additional troop surge the administration outlined last week should cost about $30 billion more per year. That’s not to advance any particular conclusion about those wars but merely to observe that the United States has in the recent past undertaken initiatives that cost dramatically more than a strong climate initiative. We did it because we could afford it, and because the political elite in the United States takes military ventures seriously and wants to see them succeed. Well, averting catastrophic climate change is important too. It’s important for humanitarian reasons, it’s important for self-interested reasons, and it’s important for foreign-policy reasons. Climate change is the defining global challenge of our time, and America is the leading global power of our time. Whether we leave a legacy of leadership that meets that challenge will be determined largely by what happens at Copenhagen and what the Senate does to live up to whatever commitments the Obama administration makes there.